Pumping station sphere handling method and system

ABSTRACT

A method and system applicable to pipeline systems for handling spheres at pumping stations. Particularly the invention serves to launch spheres into the line at the downstream side of a pumping station in predetermined relation to an interface region between different liquid products. Spheres arriving at the pumping station are detected and diverted and stored in a magazine. Previously diverted spheres in the magazine are launched successively into the downstream portion of the line in such a manner as to effectively divide different products. The method makes use of sphere detecting means in the upstream portion of the line to detect the arrival of a group of spheres, and also means for detecting the interface region between different products. Special timing means is provided for controlling the sequence with which the spheres are relaunched into the line, whereby the spacing between relaunched spheres corresponds to a particular volume.

United States Patent Grove et al.

[54] PUMPING STATION SPHERE HANDLING METHOD AND SYSTEM [72] Inventors:Marvin H. Grove; Lyle R. Van Arsdale,

both of Houston, Tex.

[73] Assignee: M 8: J Valve Company, Houston, Tex'.

[22] Filed: July 30, 1970 [2l] App]. No.: 59,573

[ 51 May 23, 1972 Primary ExaminerM. Cary Nelson AssistantExaminer-Robert J. Miller Attorney-Flehr, Hohbach, Test, Albritton &Herbert 57 ABSTRACT A method and system applicable to pipeline systemsfor handling spheres at pumping stations. Particularly the inventionserves to launch spheres into the line at the downstream side of apumping station in predetermined relation to an interface regionbetweendifferent liquid products. Spheres arriving at the pumping station aredetected and diverted and stored in a magazine. Previously divertedspheres in the magazine are launched successively into the downstreamportion of the line in such a manner as to effectively divide differentproducts. The method makes use of sphere detecting means in the upstream portion of the line to detect the arrival of a group of spheres,and also means for detecting the interface region between differentproducts. Special timing means is provided for controlling the sequencewith which the spheres are relaunched into the line, whereby the spacingbetween relaunched spheres corresponds to a particular volume.

12 Clainm, 3 Drawing Figures C2 CONTROLLER AND TlMER PUMPING STATIONSPHERE HANDLING METHOD AND SYSTEM BACKGROUND OF THE INVENTION In theoperation of modern day pipeline systems for the transmission of variousliquid products, it is common to introduce product separating spheres orplugs into the line, whereby the spheres are propelled by liquid flowbetween stations which may be many miles apart. It is also common toprovide pumping stations at regular intervals along a pipeline for thepurpose of boosting the line pressure and thus ensuring continual flowof liquid through the line. Such a station consists essentially of apump having suction and discharge pipes connected to upstream anddownstream portions of the line. When a sphere arrives at a pumpingstation it must be bypassed about the station, or it must be divertedfrom the line and the same or another sphere reintroduced into thedownstream portion of the line. Assuming that the sphere is being usedfor the purpose of separating products of different gravities, it shouldbe located and maintained at or near the interface region between theproducts. It has been observed that when such separating spheres havebeen propelled over considerable distances, there is a tendency for thesphere to lag behind the interface region, thus permitting someintermingling between the products. If the station bypass means employedserves to divert and then reintroduce the sphere back into the main linein the same general position which it previously occupied with respectto the liquid products, then the lag referred to above is notcompensated for but in fact becomes cumulative as the sphere moves pastsuccessive stations.

Aside from the operation of pumping stations, it has been proposed touse more than one sphere to obtain better separation between products.Also it has been proposed to introduce a so-called buffer liquid betweentwo-liquid products, thus providing two interface regions, with a spherebeing located at each region. In addition it has been proposed toprovide three spheres for obtaining more effective separations, with thefirst sphere being located at the first interface region, and the secondand third spheres being located at predetermined points behind the firstsphere. For example, where a buffer liquid is introduced to provide twointerface regions, it has been proposed to locate the first sphere atthe first or advancing interface region, the second sphere at or nearthe second interface region, and the third sphere a short distancebehind the second sphere. The use of several spheres in-this mannerseriously complicates the handling of spheres at pumping stations,particularly since it is necessary to launch the spheres at a relativelyrapid rate, with proper relation to the interface region. Therefore,methods and systems have not been available for performing the requireddiverting and relaunching operations, where several spheres are employedfor product separation.

SUMMARY OF THE INVENTION This invention relates generally to methods andsystems applicable to pipelines making use of flow propelled spheres toseparate liquid products. More particularly it relates to methods andsystems of this character which employ several spheres to separateproducts.

In general it is an object of the invention to provide a method andsystem of the above character which will rapidly launch a numberofspheres into the downstream portion of the line at a pumping station andin predetermined relation to an interface region between differentproducts.

Another object of the invention is to provide a method and system of theabove character which will operate to effectively launch spheres inpredetermined relation to an interface region, irrespective of any lagbetween the spheres and the interface region as received at the station.

Another object of the invention is to provide a method and system of theabove character making use of novel timing means in such a manner thatthe spheres are rapidly and successively introduced into the downstreamline portion with predetermined spacing.

Another object of the invention is to provide a method and a system ofthe above character which is capable of accurately launching spheresinto the downstream portion of the line at a relatively rapid rate, andindependent of the rate with which spheres are received.

Additional objects and features of the invention will appear from thefollowing description in which the preferred embodiment has been setforth in detail in conjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic diagramillustrating apparatus forming the present system, with electrical meansto obtain automatic cycling.

FIG. 2 is a detail in section illustrating the sphere diverting teeindicated in FIG. 1.

FIG. 3 is a diagram illustrating the various steps involved in acomplete cycle of operation.

DESCRIPTION OF THE PREFERRED EMBODIMENT The system illustrated in FIG. 1consists of the upstream line portion 10a located at the upstream sideof a pumping station, and a downstream or outgoing line portion 10b. Thepumping station may consist of the pump 11 having suction and dischargelines 12, 13 provided with valves 14 and 15. Also lines 12 and 13 may beconnected by check valve 16, which is normally closed by fluid pressure.The upstream line portion 10a is shown including the spaced spheredetectors D1 and D2, and the sphere diverter 17. This diverter may be asimple flow tee having a side duct connected to the bypass line 18. Whensubstantial flow occurs through line 18 in the direction indicated,spheres arriving at the flow tee l7 tend to be carried into the line 18.Line 18 is provided, with a flow tee 19, which has a conduit 12aconnected to the suction line 12 of the station pump 11. A grid or bars20 prevent spheres from entering conduit 12a and a wash line 26a may beprovided to aid movement of spheres past the grid. Flow tee 19 may beconstructed as disclosed and claimed in U.S. Pat. No. 3,387,483.

- The bypass line 18 also connects with the magazine tube 21, whichserves to store spheres for launching. The lower portion 21a of tube 21communicates with the downstream portion 10b, as illustrated in FIG. 1.Spheres within the tube portion 210, illustrated in dotted lines, areretained by the retractable launching pin 22. This pin is actuated byenergizing the external power operator 23, and when energized the pin isbriefly retracted to permit the nearest sphere to pass downwardly intothe downstream portion of the line 10b.

Tube portion 21a is separated from portion 21b by the normally closedvalve 26, which is shown provided with a power operator 27. Also a valve28, shown provided with power operator 29, controls communicationbetween the portion 21b of the tube and the bypass line 18. The internaldiameter of the magazine tube is substantially greater than the diameterof the spheres, whereby when spheres are deposited into the magazinethey move downwardly by gravity.

Launching of the spheres is assisted by momentarily introducing a liquidstream into the region immediately above the lowermost sphere, at thetime the pin 22 is retracted. Thus pipe 31 connects through one wall ofthe tube portion 21a, and its other end connects with the discharge line13 of the pump 11. Flow of liquid through pipe 31 is controlled by thevalve 32, which may be provided with operating means as indicated. Whenvalve 32 is operated simultaneously with retraction of pin 22, a streamof liquid is introduced into the space immediately above the lowermostsphere, thus propelling this sphere into the main line and tending tohold back the sphere immediately above the same until the liquid streamis discontinued. In this manner the sphere is rapidly and positivelythrust into the line.

It is desirable to provide a shutoff valve 33 in the discharge line 13from the pump 11. Also it is desirable to provide a block valve 34 in anintermediate portion 100 of the line, or in other words, that portion ofthe main line extending from the diverter 17 to the magazine tube 21.

At a point on the discharge side of pump 11 suitable detecting means isprovided which will detect an interface region between products ofdifferent gravities. Such a detector is illustrated schematically at 36and is located adjacent the lower end of the launching tube. Knowndevices capable of continuously monitoring changes in specific gravitymay make use of means for continuously diverting and reintroducing smallquantities of liquid together with hydrometer means which indicates anincrease or decrease in specific gravity.

For partial or complete automation it is desirable to provide timers T1and T2 which respond to signals or demands from detector D1 and D2, andwhich perform operations as will be presently described. It is alsodesirable to provide electronic circuitry including controllersschematically indicated at C1 and C2, which receive and transmit demandsas will be presently described. These controllers may comprise knowntypes of electrical components, including amplifiers and the like.

To facilitate the following description the valves 28 and 26 have beendesignated V1 and V2 respectively, the valve 32 as V3, and the valve 34as V4.

A suitable sphere diverter 17 is shown in FIG. 2. It consists of spaceddiverter bars 36 which are attached to shaft 37. When these bars are inthe position shown in solid lines, a sphere is diverted from line a intothe bypass line 18. When the bars are swung to the position shown indotted lines, the spheres are permitted to pass through the line portion100 and cannot enter the bypass pipeline 18. When the station is innormal operation the bars 36 are in the position shown in solid lines.The shaft 37 may be provided with hydraulic or other type of poweroperator to permit remote operation.

While a flow tee with diverter bars may be desirable, it is notessential. A simple flow tee without bars may be used since the spherewill follow the direction of liquid flow.

In practice the sphere detectors D1 and D2 are located a predetermineddistance apart, as for example a distance which provides a volumebetween sphere centers of ten barrels. Timers T1 and T2 are constructedto provide an upcount, and when initiated by a command a downcount at arelatively slower speed, as for example at a rate one fourth theupcount. Thus, if the complete upcount requires N seconds, the completedowncount may require four times N seconds.

A complete cycle of operation can now be described as follows. It willbe assumed that liquid products (e.g., liquid petroleum products)flowing through the main line are being separated by the use of thethree spheres, the first of which is intended to be at the advancinginterface region. When the first of the three spheres passes thedetector D1, a command 41 is sent to both timers T1 and T2, thusstarting both timers on an upcount. At the same time command 42 is sentfrom detector D1 to the controller C2 whereby this controller causes thepower operator 29 of valve V1 to open the same. After operating thedetector D1 the first sphere operates detector D2, and this sends acommand 43 to both timers T1 and T2 to stop the same. Since flow is nowoccurring through the lines 18 and 12 to the suction side of the pump11, the sphere after passing detector D2 is caused to pass through theline 18, and to the entrance end of the magazine tube 21. At this timevalve V1 is open and the sphere is delivered into the upper portion 21bof the magazine. After the first sphere passes the detector D2 thegravity of the products is being continuously monitored by the gravitydetecting device 36, and this device detects arrival of an interfaceregion. It may be explained that the interface region generally reachesthe monitoring device 36 before the first received sphere reaches themagazine tube 21. In response to a command 44 from the device 36 thecontroller C1 energizes operator 23 to momentarily retract pin 22, andalso momentarily opens valve V3, thus causing the lowemiost sphere to bepropelled into the downstream portion 10b of the main line. The commandissued by the controller C1 also issues command 46 to timer T1 to starta countdown. As previously stated the rate of the countdown issubstantially less than the countup and may be set according to thespacing desired between the launching of the first and second spheres.Thus, if the volume between detectors D1 and D2 were ten barrels and itis desired to relaunch the first and second spheres at a spacingcorresponding to a volume of forty barrels, the countdown would be at arate one fourth the rate of countup. When timer Tl reaches zero itissues a command 47 to the controller C1, whereby pin 22 is retractedand valve V3 momentarily opened to launch a second sphere into the line.Also T1 issues command 48 to T2 to start a second countdown. Thiscountdown can be at the same rate as the countdown for timer T1 assumingthat the spacing between the second and third sphere is to be the sameas the spacing between the first and second. When timer T2 has returnedto zero at the end of its countdown, it issues command 49 to thecontroller C1 whereby this controller again momentarily opens the valveV3 and retracts pin 22 to launch the third sphere.

During or immediately after the time the three spheres are beinglaunched, the three spheres which have been received by the system fromthe upstream line portion have been diverted through line 18' anddelivered into the upper magazine portion 211;. Command 49 from timer T2is shown also being applied to the controller and timer C2. The timingmeans of this controller is set whereby the operator 29 of valve V1 isenergized to close the same. About the same time the operator 27 forvalve V2 is actuated to open the same and retain this valve open asufiicient period of time for all of the spheres in the upper tubeportion 21b to gravitate downwardly into the lower tube portion 210.Then the controller C2 causes the operator 27 to close the valves V1 andV2. The system is now ready to receive another group of spheres.

The schematic diagram of FIG. 3 illustrates the sequence of operationsdescribed above. The sequence of operations of the various components isshown by the vertical lines, while operating steps are shown in the lefthand column.

It will be evident from the foregoing that the present inventionprovides a method and system which will effectively bypass pumpingstations of pipelines with relaunching of spheres in such a manner as topromote optimum separation between liquid products. Because of themagazine storage feature the method and system is capable of relaunchingspheres at a relatively rapid rate, that is, independent of the ratewith which the spheres are received. The relaunching of the spheres intothe line is controlled by the hydrometer monitoring, thus making itpossible to correct any lag between the interface region and the spheresas received at the station.

In addition to the parts described above it is desirable to provide anormally closed access extension 51 which can be opened to insert,remove, inspect, or replace spheres. Also it is desirable to provide avalve 52 in the suction line 12 whereby when valve V4 is opened, valves33 and 52 can be closed to isolate the pump. For automated shutdown thecontroller 53, which is responsive to a circuit 54 adapted to sense anelectrical power failure, issues command 55 to the power operator of V4to open the same. Means such as a limiting switch on V4 sends command 56to both the operators of valves 33 and 52 to close the same, thusisolating the pump from the line.

It will be evident that the method and system described above can bemodified in certain respects. For example, the number of sphereslaunched in one overall cycle can be varied, or in some instances wheremultiple sphere separation is not desired, a single sphere can belaunched. The launching of spheres, involving operation of pin 22 andvalve V3 may be carried out manually or by manual supervision. Even withfull automatic operation it is desirable to provide for monitoring, withsuitable indicating means at a monitoring station whereby all operationsare made known to a supervisor. This can be associated with suitablemeans whereby the supervisor may at any time intervene and overridevarious operations as desired.

We claim:

1. A method of handling product separating spheres being fiow propelledalong a main pipeline which conducts a plurality of products ofdifferent specific gravities separated at one or more interface regions,the method making use of a magazine for retaining and storing aplurality of spheres in readiness to be released into the downstreamportion of the line, the steps of detecting the arrival of an interfaceregion between two liquid products at a point near the station,releasing a sphere from the magazine, to launch the same into thedownstream portion of the line in accordance with such detection wherebythe sphere is launched into said interface region, and diverting spheresfrom the upstream portion of the line and supplying the same to themagazine.

2. A method as in claim 1 in which at least one additional sphere islaunched from the magazine into the downstream portion of the line inpredetermined spaced relationship with the first released sphere.

3. A method of handling product separating spheres being flow propelledalong a main pipeline which conducts a plurality of products ofdifferent specific gravities separated at one or more interface regions,the method making use of means inserted in an upstream portion of theline to divert incoming spheres into a station pump bypass line and amagazine for retaining and storing a plurality of spheres in readinessto be released into the downstream portion of the line, the steps ofdiverting a sphere from the main line into a bypass line, deliveringsuch diverted sphere into the storage magazine, detecting the arrival ofan interface region at a point near the station pump, releasing a spherefrom the magazine into the downstream portion of the line in response tosuch detection whereby it is launched into said interface region, andthen releasing a second sphere from the magazine into the downstreamportion in predetermined spaced relationship with the first releasedsphere.

4. A method as in claim 3 in which a third sphere is released from themagazine after release of the second sphere, the third sphere beingreleased and introduced into the downstream portion of the line inpredetermined relationship to the first and second released spheres.

5. A method as in claim 3 in which diverted spheres are stored in themagazine and spheres diverted in a preceding cycle of operation releasedinto the downstream portion of the line.

6. A method as in claim 5 in which the time required for the arrival ofthe first one of two successive spheres at spaced points along theupstream portion of the line is noted and the spacing between thereleased spheres is determined by reference to such timing.

7. A system for the handling of product separating spheres at a pumpingstation where the station is connected to receive liquid from anupstream line portion and to deliver liquid into the downstream portionof the line, a storage magazine adapted to store a plurality of spheres,means for releasing spheres from the storage means and for introducingthe same into the downstream portion of the line, means for divertingspheres arriving at the pumping station from the upstream portion of theline, and means for introducing such spheres into the magazine.

8. A system for the handling of product separating spheres at a pumpingstation where the station is connected to receive liquid from anupstream line portion and to deliver liquid into the downstream portionof the line, a storage magazine adapted to store a plurality of spheres,means for releasing spheres from the storage means and for introducingthe same into the downstream portion of the line, and means responsiveto the arrival of an interface region between liquid products at a pointnear the pumping station for controlling the release of spheres from themagazine.

9. A system for the handling of product separating spheres at a pumpingstation where the station is connected to receive liquid from anupstream line portion and to deliver liquid into the downstream portionof the line, the system including storage means for storing spheresdiverted from the line, means for diverting incoming spheres from theupstream portion of the line and for delivering the same into thestorage means, and means for successively releasing spheres from thestorage means and for introducing the same into the downstream portionof the line, the storage means comprising two first and second spacesserving to store two separate first and second groups of spheres, thefirst group representing spheres previously diverted from the line andthe second group representing spheres immediately diverted from theline, and a valve when closed serving to separate said spaces and saidgroups of spheres and when open permitting the first group of spheres toprogress into the second space of the storage means for introductioninto the downstream portion of the line. I

10. A system for the handling of product separating spheres at a pumpingstation where the station is connected to receive liquid from anupstream line portion and to deliver liquid into the downstream portionof the line, the system including storage means for storing spheresdiverted from the line, means for diverting incoming spheres from theupstream portion of the line and for delivering the same into thestorage means, and means for successively releasing spheres from thestorage means and for introducing the same into the downstream portionof the line, the storage means comprising an upright magazine tube, thelower end of the tube being in communication with the downstream portionof the line, an additional valve at the upper end of the tube adapted tobe opened to permit introduction of spheres, said first named valvebeing disposed intermediate the ends of the tube to divide the tube intoupper and lower first and second spaces, and a retractable sphereretaining pin at the lower end of the magazine tube.

11. A system as in claim 10 in which a liquidsupply pipe is incommunication with the magazine tube at a point intermediate the twolowermost spheres in the same, said pipe serving as means forintroducing liquid to urge the lowermost sphere downwardly into thedownstream line portion when the retaining pin is retracted.

12. A system for handling product separating spheres being flowpropelled along a pipeline used for conducting a plurality of liquidproducts of different specific gravities separated at one or moreinterface regions, the system being applicable to pipelines at pumpingstations where the station has suction and discharge connections toupstream and downstream portions of the line, the system comprising twosphere detectors on the upstream portion of the line, the detectorsbeing spaced apart a predetermined distance representing a predeterminedvolume, two timing devices responsive to demands from said spheredetectors, each device providing an upcount and a downcount after theupcount is terminated, a sphere storage magazine consisting of amagazine tube having its lower end communicating with the downstreamportion of the line,'said tube having its upper portion adapted toreceive spheres diverted from the line and having its lower portionadapted to store spheres previously diverted from the line, means forreleasing spheres successively from the lower portion of the tube intothe downstream portion of the line, means downstream from the pumpingstation but upstream from the point of communication of the magazinetube with the downstream portion of the line for detecting passing of aninterface region between products of different specific gravities, meansresponsive to such detection for actuating and retracting said sphereretaining pin and means responsive to a demand from said gravityindication for causing successive downcounts by said timing devices andfor releasing successive spheres after the first released sphere atintervals whereby successive spheres are introduced into the downstreamportion of the line at predetermined positions relative to the firstsphere.

1. A method of handling product separating spheres being flow propelledalong a main pipeline which conducts a plurality of products ofdifferent specific gravities separated at one or more interface regions,the method making use of a magazine for retaining and storing aplurality of spheres in readiness to be released into the downstreamportion of the line, the steps of detecting the arrival of an interfaceregion between two liquid products at a point near the station,releasing a sphere from the magazine to launch the same into thedownstream portion of the line in accordance with such detection wherebythe sphere is launched into said interface region, and diverting spheresfrom the upstream portion of the line and supplying the same to themagazine.
 2. A method as in claim 1 in which at least one additionalsphere is launched from the magazine into the downstream portion of theline in predetermined spaced relationship with the first releasedsphere.
 3. A method of handling product separating spheres being flowpropelled along a main pipeline which conducts a plurality of productsof different specific gravities separated at one or more interfaceregions, the method making use of means inserted in an upstream portionof the line to divert incoming spheres into a station pump bypass lineand a magazine for retaining and storing a plurality of spheres inreadiness to be released into the downstream portion of the line, thesteps of diverting a sphere from the main line into a bypass line,delivering such diverted sphere into the storage magazine, detecting thearrival of an interface region at a point near the station pump,releasing a sphere from the magaZine into the downstream portion of theline in response to such detection whereby it is launched into saidinterface region, and then releasing a second sphere from the magazineinto the downstream portion in predetermined spaced relationship withthe first released sphere.
 4. A method as in claim 3 in which a thirdsphere is released from the magazine after release of the second sphere,the third sphere being released and introduced into the downstreamportion of the line in predetermined relationship to the first andsecond released spheres.
 5. A method as in claim 3 in which divertedspheres are stored in the magazine and spheres diverted in a precedingcycle of operation released into the downstream portion of the line. 6.A method as in claim 5 in which the time required for the arrival of thefirst one of two successive spheres at spaced points along the upstreamportion of the line is noted and the spacing between the releasedspheres is determined by reference to such timing.
 7. A system for thehandling of product separating spheres at a pumping station where thestation is connected to receive liquid from an upstream line portion andto deliver liquid into the downstream portion of the line, a storagemagazine adapted to store a plurality of spheres, means for releasingspheres from the storage means and for introducing the same into thedownstream portion of the line, means for diverting spheres arriving atthe pumping station from the upstream portion of the line, and means forintroducing such spheres into the magazine.
 8. A system for the handlingof product separating spheres at a pumping station where the station isconnected to receive liquid from an upstream line portion and to deliverliquid into the downstream portion of the line, a storage magazineadapted to store a plurality of spheres, means for releasing spheresfrom the storage means and for introducing the same into the downstreamportion of the line, and means responsive to the arrival of an interfaceregion between liquid products at a point near the pumping station forcontrolling the release of spheres from the magazine.
 9. A system forthe handling of product separating spheres at a pumping station wherethe station is connected to receive liquid from an upstream line portionand to deliver liquid into the downstream portion of the line, thesystem including storage means for storing spheres diverted from theline, means for diverting incoming spheres from the upstream portion ofthe line and for delivering the same into the storage means, and meansfor successively releasing spheres from the storage means and forintroducing the same into the downstream portion of the line, thestorage means comprising two first and second spaces serving to storetwo separate first and second groups of spheres, the first grouprepresenting spheres previously diverted from the line and the secondgroup representing spheres immediately diverted from the line, and avalve when closed serving to separate said spaces and said groups ofspheres and when open permitting the first group of spheres to progressinto the second space of the storage means for introduction into thedownstream portion of the line.
 10. A system for the handling of productseparating spheres at a pumping station where the station is connectedto receive liquid from an upstream line portion and to deliver liquidinto the downstream portion of the line, the system including storagemeans for storing spheres diverted from the line, means for divertingincoming spheres from the upstream portion of the line and fordelivering the same into the storage means, and means for successivelyreleasing spheres from the storage means and for introducing the sameinto the downstream portion of the line, the storage means comprising anupright magazine tube, the lower end of the tube being in communicationwith the downstream portion of the line, an additional valve at theupper end of the tube adapted to be opened to permit introductiOn ofspheres, said first named valve being disposed intermediate the ends ofthe tube to divide the tube into upper and lower first and secondspaces, and a retractable sphere retaining pin at the lower end of themagazine tube.
 11. A system as in claim 10 in which a liquid supply pipeis in communication with the magazine tube at a point intermediate thetwo lowermost spheres in the same, said pipe serving as means forintroducing liquid to urge the lowermost sphere downwardly into thedownstream line portion when the retaining pin is retracted.
 12. Asystem for handling product separating spheres being flow propelledalong a pipeline used for conducting a plurality of liquid products ofdifferent specific gravities separated at one or more interface regions,the system being applicable to pipelines at pumping stations where thestation has suction and discharge connections to upstream and downstreamportions of the line, the system comprising two sphere detectors on theupstream portion of the line, the detectors being spaced apart apredetermined distance representing a predetermined volume, two timingdevices responsive to demands from said sphere detectors, each deviceproviding an upcount and a downcount after the upcount is terminated, asphere storage magazine consisting of a magazine tube having its lowerend communicating with the downstream portion of the line, said tubehaving its upper portion adapted to receive spheres diverted from theline and having its lower portion adapted to store spheres previouslydiverted from the line, means for releasing spheres successively fromthe lower portion of the tube into the downstream portion of the line,means downstream from the pumping station but upstream from the point ofcommunication of the magazine tube with the downstream portion of theline for detecting passing of an interface region between products ofdifferent specific gravities, means responsive to such detection foractuating and retracting said sphere retaining pin and means responsiveto a demand from said gravity indication for causing successivedowncounts by said timing devices and for releasing successive spheresafter the first released sphere at intervals whereby successive spheresare introduced into the downstream portion of the line at predeterminedpositions relative to the first sphere.